Generally, wires used for wiring electric circuits use structures such as a wire 200 as shown in FIG. 5(a), in which a metal element line (single line) 50 made of a linear shape conductive metal material is covered with an insulation covering material 60, and such as a wire 201 as shown in FIG. 5(b), in which plural metal element lines 51 are bundled and covered with a covering material 60 at the periphery of the lines. High melting point metals such as copper are used for those metal element lines in view to such as lowness of electrical resistance rate, material costs, and easiness of availability. The copper, however, has a high melting point of 1085 degrees Celsius, and where heat is generated due to overcurrent flow through an electric circuit, the covering material may catch fire before current supply is cut off by fusing the copper line.
To prevent the electric wire from accidentally catching fire due to overcurrent, a flame retardant cover material is used these days to correspond this matter, but an ordinarily available resin based covering material has a limitation in terms of heat resistibility.
In meantime, Patent Document #1 discloses an electric wire having an overcurrent cutoff function made of a metal whose melting point is equal to or less than 700 degrees Celsius, in lieu of a fusible link electric wire as an electric wire having a function equivalent to a fuse.